It is proposed to determine the effects of dietary zinc supplementation on zinc nutritional status and physical growth of preschool children who have low height percentiles and laboratory evidence of zinc deficiency. Detailed biochemical investigations of the zinc nutritional status of preschool children will be undertaken with the measurement of zinc concentrations in plasma, erythrocytes, hair, urine and saliva and measurement of the activity of certain zinc-dependent enzymes. The relative value of these potentially useful indices of zinc status will be assessed. It is planned to compare the zinc nutritional status of breast-fed and formula-fed infants, and to determine the effect of different feeding regimens on zinc levels in premature infants in early post-natal life. The long-term effects of zinc therapy in acrodermatitis enteropathica will be determined. BIBLIOGRAPHIC REFERENCES: Hambidge, K.M. and Walravens, P.A.: Zinc deficiency in infants and preadolescent children. In: Trace Elements in Human Health and Disease, ed., A.S. Prasad, Academic Press, Inc., Vol. 1, Chapter 2, 1976. Hambridge, K.M., Walravens, P.A., Brown, R.M., Webster, J., White S., Anthony, M. and Roth, M.L.: Zinc nutrition of preschool children in the Head Start program. Am. J. Clin. Nutr., 29:734-738, 1976.